This study investigated the effects of astaxanthin (ASTA) on testosterone synthesis and mitochondrial function in testicular Leydig cells of aging roosters. ASTA significantly enhanced Leydig cell viability ( P < 0.05) and increased testosterone production at concentrations of 2.5–20 μg/mL ( P < 0.05), with the optimal effect observed at 5 μg/mL ( P < 0.01). At this concentration, ASTA significantly upregulated the mRNA and protein expression of key steroidogenic enzymes, steroidogenic acute regulatory (StAR), cholesterol side-chain cleavage cytochrome (P450scc), 3β-hydroxysteroid dehydrogenase (3β-HSD), 17β-hydroxysteroid dehydrogenase (17β-HSD) ( P < 0.01), and steroidogenic factor-1 (SF-1) ( P < 0.05). ASTA also significantly elevated the activities and mRNA expression of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-PX) ( P < 0.01), reduced reactive oxygen species (ROS) levels ( P < 0.05), and decreased malondialdehyde (MDA) content ( P < 0.01). Furthermore, ASTA treatment significantly improved mitochondrial membrane potential (MMP), adenosine triphosphate (ATP) content and mitochondrial DNA (mtDNA) copy number ( P < 0.01), increased the expression of mitochondrial biogenesis regulators peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), nuclear respiratory factor-1 (NRF1), and mitochondrial transcription factor A (TFAM) ( P < 0.01), and significantly suppressed apoptosis ( P < 0.05), as evidenced by increased B-cell lymphoma-2 (Bcl-2) expression ( P < 0.01) and reduced expression of Bcl-2-associated X protein (Bax), cysteinyl aspartate specific proteinase-3 (caspase-3), and apoptosis-inducing factor (AIF) ( P < 0.01). These results indicate that ASTA enhances testosterone synthesis in aging rooster Leydig cells by reducing oxidative stress, improving mitochondrial function and biogenesis, upregulating steroidogenic genes, and inhibiting mitochondrial-related apoptosis.
Liu et al. (Sun,) studied this question.